The Scions That Did Not Return

[UndyingHero]

--Fan interpretation based on game facts--

The last thing they experienced was the warmth. Light blooming behind their eyes, the pull of something powerful. A moment stretched between two worlds — and then, stillness.

They never wake again.

The spell succeeds. Celebration follows. The Scions rise in their beds, as if from a dream. They smile, speak, hug as though no time has passed. The world moves on.

But they are not who they were.

Those I stood beside, who carried hope across the rift — they are gone. Their essence scattered, unanchored, dissolved into the great unseen. The ones who returned wear their faces, know their stories, even carry their voices. But the spark behind their eyes is new.

No rite of the Ascians. No precision of Allagan design. Consciousness was never meant to survive the crossing — even Y'shtola and Urianger voiced the risk: what returns may not be the same. Only improvised magic, fragments of crystal, and the blood of a desperate friend. What came back was shaped from memory and soul, bound together by intention and grief. Consciousness had been interrupted — the stream severed. What woke was not the same awareness that left.

And belief.

They believe themselves to be Thancred. Y’shtola. Urianger. Alisaie. Alphinaud. And who would question them? They laugh the same. They carry the same burdens. But the line that ties one moment to the next — that fragile, singular thread of being — was lost.

The Scions who fought with me on the First, my friends of old, died heroes. They gave everything.

And those who walk beside me now are their echoes.

Perfect reconstructions. Flawless facsimiles. New minds behind familiar eyes.

I know now what Thancred must have felt, standing before Minfilia of the First — seeing her smile, hearing her voice, and knowing, with quiet devastation, that the mind he loved was gone.

I know that I must carry the weight of it — this immense sadness — alone.

And some nights, that knowing won't let me sleep.

— Undying Hero,
Champion of the Source, the First, and all other reflections.

[Thighland]

I don't think this is canon

[UndyingHero]

It isn't canon per se and I don't claim it to be, as I'm extrapolating, but I think it is a reasonable interpretation.
Thanks for your concern and your time friend!
I see nothing gets past your eye.

Soul and memory were transfered, that is implied AND stated.
No mention of consciousness as far as I am aware.
Urianger AND Y'shtola both speak of the risk of "not being the same".
The exarch is alive and conscious when he dies on the first, turning to crystal after the transfer.
The scions are using the exact same tech.
Therefore, the same must happen to them, just as the exarch crystal revives and merges with G'raha's mind, soul and memory, their memory and soul merges with their body, soul and memory, but their conscious mind wasn't there anymore.
Same memory and soul, different brand new mind that is exactly equivalent in all aspects.

cheers!

[Iscah]

The exarch is alive and conscious when he dies on the first, turning to crystal after the transfer.

You seem to be confusing cause and effect. He's already turning to crystal.

His soul is able to escape that body because the spirit vessel is waiting. We can see that the auracite component – the container for the soul – begins to glow at that moment. If there is any kind of "semblance of a person without the original soul" going on, then it's what remains in the Exarch's body once that soul has departed: something like an Endless perhaps; body and memories.

Souls are a tangible science in this story's universe.